Survey of the methods to select fault line in neutral point ineffectively grounded power system

Neutral point ineffectively grounded power system is widely used in 3～66 kV power distribution system in China.In this power system,the single-phase-to-earth fault occurs frequently in distribution,thus how to detect the fault line with great accuracy and high efficiency is an important subject in protective relaying of power system.Reviewing the history of the methods to select the fault line in neutral point ineffectively grounded power system,this paper summarizes the existing theories of fault line selection and gives the conclusions.